The invention relates to a releasable binding for a slideboard, comprising a first part integral with a shoe and a second part which is intended to be fastened to the slideboard and in which the first part is retained at least approximately at its two ends on the second part by means of moveable components held in engagement with the first part under the action of at least one spring, so as to free the shoe in the event of a forward or backward fall and under torsion.
Such a binding is known from patent AT 315 040. The sole of the shoe is provided with a U-shaped metal piece having receptacles, in which are engaged retaining fingers, one of which is mounted slideably, against the action of a spring, in a housing fastened to the ski. A binding of the same type is described in the patent AT 317 738. The patent U.S. Pat. No. 3,957,280, the content of which is incorporated by reference, likewise describes a shoe of the same type, in which the two retaining fingers are mounted slideably against the action of one or two springs. In the bindings as described in the patent U.S. Pat. Nos. 3,834,723 and 4,191,395, the contents of which are incorporated by reference, the sliding locking fingers are mounted in the sole of the shoe and cooperate with surfaces formed respectively in two components and in one component fastened to the Ski. A solution of the same type as that described in patent U.S. Pat. No. 3,957,280 was readopted in the patent U.S. Pat. No. 4,245,409, the content of which is incorporated by reference. These designs make it possible to dispense completely with fitting the binding to the size of the shoes, that is to say to have a truly universal binding and to make it possible to reduce the number of components. By contrast, these bindings are not practical, since they have a major disadvantage: damage to the sensitive surfaces of the sole of the shoe, that is to say to the surfaces involved directly in releasing the binding in the event of a fall. These bindings nevertheless have a useful advantage which is the possibility of shaping the ends of the shoe very freely, in particular of dispensing with the front and rear footplates which are necessary for conventional ski bindings, and of rounding the lower face of the sole at its ends so as to make walking easier.
In order to overcome the disadvantages of shoes with an integrated binding according to the prior art mentioned above, it was proposed to produce a binding in three parts, namely a first part intended to be fastened to the slideboard, a second part integral with the shoe and a third part connecting the first and second parts, only the first and third parts being arranged so as to form a connection which is releasable in the event of a fall. The shoe may be conventional. Such bindings are described in the patents U.S. Pat. Nos. 3,918,732 and 4,191,395, the contents of which are incorporated by reference and in the patent FR2 659 565. These bindings are relatively bulky and are intended for shoes of the conventional type comprising a front footplate and a rear footplate for their bindings on the intermediate part. It is still necessary for a means for binding the shoe to the intermediate part to be fitted to the shoe size.
The object of the invention is to preserve the independence of the torsion and forward-fall release means which are found in the bindings with a thrust piece and with a heel piece, thus making it possible to control the releasing forces more effectively in each case.
The binding according to the invention is defined in that the first part, integral with the shoe, has, at the rear, a pair of lateral pegs, and in that the second part, integral with the slideboard, comprises, at the rear, a moveable component consisting of a stirrup mounted pivotably about an axis transverse to the binding and pivotably about a vertical axis, the arms of this stirrup coming into retention with the pegs of the first part and coming to bear on these pegs with ramps allowing the pegs to cause the stirrup to tilt counter to the action of the spring in the event of a forward fall.
According to one embodiment of the invention, the first part is rigid and integral with the sole and has, at the front, front vertical bearing surfaces and the second part, integral with the slideboard, comprising, at the front, a moveable component consisting of a jaw intended for bearing frontally and vertically on the bearing surfaces of the first part, this jaw being capable of tilting in a vertical plane and in a horizontal plane against the action of said spring.
In this case, the part integral with the sole of the shoe does not have a sensitive surface liable to disrupt the release of the binding.
Release under torsion is preferably controlled solely by the jaw. For this purpose, the stirrup bears on the spring, more specifically on a slide against which the spring reacts, with a part rounded in an arc of a circle and centered on a vertical pivotal axis of the stirrup, in such a way that the pivoting of the stirrup does not alter the compression of the spring.
The jaw is preferably articulated by means of a knuckle joint allowing it to tilt in all directions.
The stirrup is preferably mounted pivotably about a horizontal axis in a stirrup mounted pivotably about a central pivot, and the horizontal pivot axis of the retaining stirrup is located above its base with which the stirrup bears against its slide.
Shoe removal can be carried out by means of a shoe removal lever articulated in the rear of the stirrup and acting on the stirrup by means of a thrust piece in order to cause said stirrup to tilt against the action of the spring.
Forward-fall release is controlled by the stirrup which operates in the manner of a lever loaded by the pegs. This method of retention is insensitive to the surface quality of the pegs and of the parts of the hook-shaped stirrup.
The stirrup therefore provides no resistance to the release of the binding under torsion. The shoe first escapes from the jaw, and then the pegs escape from the stirrup, without subjecting the latter to tilting stress.
The first part integral with the shoe could be the sole itself. The pegs would be fastened to the sole, the front of which would have a conventional footplate retained by a stop piece of a conventional type.